Will Iraq strut or stumble after U.S. soldiers leave? Dangerous times are ahead for cities like Kirkuk

The citizens of Kirkuk - Arabs, Turkomans and Kurds - but and sell alongside one another in the ancient market, which is patrolled by Iraqi police.

From the crumbling Assyrian ramparts of Kirkuk's 3,000-year-old citadel, the giant open-air market snaking around its base seems the very picture of communal harmony: Kurdish, Turkoman and Arab shoppers navigate through narrow lanes, past stalls selling everything from fresh fruit to plastic flowers. My police escort, a Kurd, beams down with pride. "This is the perfect Iraq," he says. "Nobody angry, everybody happy."

At ground level, the market smells of bird droppings and open drains, and the mood is murkier. An Arab vendor of pomegranates loudly endorses my escort's claim that Kirkuk is a microcosm of an ideal Iraq. But when...